Japan on Tuesday protested to Beijing after an inspection ship chased down a Japanese ocean surveying vessel in the East China Sea, the coastguard said.
The incident took place on Monday in the East China Sea, about 320 kilometres (198 miles) northwest of Japan’s southern Amami Oshima island, he said.
“The Chinese ship Haijian 51 approached the Japanese surveying vessel, the Shoyo, and chased it down for hours while demanding it leave Chinese waters,” said the Japanese official who asked not to be named.
“It was the first time that a Chinese ship has demanded Japan’s survey vessel stop its work in its EEZ (exclusive economic zone),” he said, adding that the Japanese ship was conducting its oceanographic survey.
“The Japanese Foreign Ministry on Tuesday lodged a protest against Beijing over the incident,” he added.
The Haijian 51, which says “China Marine Surveillance” on its side, is believed to be the Chinese government’s inspection ship.
Ties between Tokyo and Beijing have been strained over territorial disputes in the East China Sea.
There are four controversial Chinese gas fields in the East China Sea that Japan says extend into its own EEZ.
The two countries are also disputing sovereignty of the Senkaku islands, known as the Diaoyu islands in Chinese, which lie between Japan and Taiwan.
The incident followed China’s helicopter fly-bys near Japan’s Okinawa island last month when Japanese naval ships spotted and followed the largest Chinese flotilla of warships so far to sail between Japanese islands.
The Chinese ships did not pass through Japan’s territorial waters but their voyage was seen as provocative by many in Japan, which has watched with unease its Asian rival’s build-up of military muscle.
Tokyo has lodged a protest with Beijing after a Chinese naval helicopter flew within 90 metres (300 feet) of one of its naval ships on April 23 in the second such incident last month, Japan’s defence ministry said earlier.